oscarliang.com

Oscar Liang (oscarliang.com) is a blog for FPV drone pilots and RC hobbyists, built around two things: practical tutorials and hands-on product reviews. If you fly quadcopters or multirotors and want to learn how to build, tune, or troubleshoot them — or want a hobbyist's opinion before buying gear — it's aimed at you. If you're looking for a store, a course platform, or general consumer drone news, it isn't that.

What the site covers

The site describes itself as "FPV Drone Tutorials and Reviews, a blog for RC hobbyists to get latest information about quadcopter and multirotor products and technology development." In practice that breaks down into:

• Tutorials — how-to guides for FPV work, including tool use and testing procedures.
• Reviews — evaluations of specific products, often receivers, video transmitters, and flight controllers.
• Reference material — charts and technical explainers, such as FPV channel and frequency tables.
• Technology news — updates on multirotor products and development.

Who writes it and who it's for

The blog is written by Oscar Liang and published in English (en-GB). The stated audience is RC hobbyists, with a focus on quadcopter and multirotor pilots. The tone and subject matter assume you're already in the hobby or getting into it — you'll get more out of it if you know what a receiver or a flight controller does than if you're shopping for a first camera drone.

Examples of the content

Recent posts give a clear picture of the mix:

The multimeter tutorial is a good sample of the approach: it treats a cheap, basic tool as essential kit for anyone getting into FPV or electronics, and walks through how to use it to test a drone. That's the pattern — specific, tool-and-component level, written for someone who already owns or is about to own the hardware.

When it's worth following

Follow it if you want:

• Step-by-step help with FPV hardware, testing, and builds.
• Reviews of specific components before you buy.
• Technical reference data you'll come back to (like frequency charts).

Look elsewhere if you want beginner-friendly buying advice for consumer camera drones, video-first content, or a structured course. The site is a blog, so expect articles rather than a curriculum.

If you're new to Ahrefs and want to run your first SEO audit, the fastest path is: open Site Explorer, enter your target URL, review the Overview for a health snapshot, then dig into Organic Keywords, Top Pages, and Site Audit to find specific problems. From there, build a short prioritized to-do list instead of trying to fix everything at once.

This tutorial walks through that workflow using a realistic starting scenario, explains what the numbers mean, and shows how to turn findings into actions.

Before You Start: Pick a Narrow Scope

A common beginner mistake is auditing an entire large website on day one. The reports become overwhelming, and you can't tell which issues matter.

Instead, choose one of these starting points:

• A single important page (your homepage or a key product/service page)
• A small site (under ~50 pages, e.g., a personal blog or small business site)
• One section of a bigger site (e.g., /blog/)

For this tutorial, assume you're auditing a small business site with about 30 pages. The same steps scale up later.

You'll need an Ahrefs account to follow along. Ahrefs offers paid plans, and pricing and feature limits change over time, so check the current Pricing page for what's included in each tier before committing.

Step 1: Enter Your Target in Site Explorer

Site Explorer is Ahrefs' core tool for analyzing any website or URL.

1. Open Site Explorer from the top navigation.
2. In the search box, paste your domain (e.g., example.com).
3. Choose the Exact URL or Domain mode depending on scope. For a full-site view, use Domain or Prefix; for a single page, use Exact URL.
4. Press Enter.

You'll land on the Overview report. Don't try to absorb everything — focus on four numbers first.

Reading the Overview Snapshot

Important caveat: Ahrefs' traffic and keyword numbers are estimates based on its own data. They won't match Google Search Console or your analytics exactly. Treat them as directional, not absolute.

Step 2: See What You Already Rank For

Go to Organic Keywords in the left sidebar. This shows queries where your site appears in search results.

Sort by Traffic (descending) to see which pages bring the most estimated visitors. Then look for:

• Keywords ranking in positions 4–15 — these are often the easiest wins. A small content or on-page improvement can push them onto page one.
• Keywords with high volume but low position — potential opportunities if the topic is relevant.
• Irrelevant keywords — if you rank for something off-topic, it may signal thin or mismatched content.

Write down 5–10 of the position 4–15 keywords. These become your first optimization targets.

Step 3: Find Your Best and Weakest Pages

Open Top Pages. This ranks your URLs by estimated organic traffic.

Look for two things:

1. Your top performers — understand what topics and formats work. Can you create more content like this?
2. Pages with traffic but poor rankings — these may need on-page fixes (title, headings, internal links).

If a page gets zero traffic and targets a topic you care about, it's a candidate for a rewrite or consolidation.

Step 4: Run a Technical Site Audit

Now move to Site Audit. This crawls your site and flags technical and on-page issues.

1. Click Site Audit → New project.
2. Enter your domain and set crawl settings (default is usually fine for a small site).
3. Start the crawl and wait for it to finish.

Once complete, you'll see a Health Score and a list of issues grouped by category.

Which Issues to Fix First

Not all issues are equal. Prioritize in this order:

Ignore low-impact warnings (like minor meta description length) until the big items are handled.

Step 5: Turn Findings Into a To-Do List

You now have raw data. Convert it into a short, actionable list. Example:

1. Fix 3 broken links found in Site Audit.
2. Rewrite title tags on 5 pages with duplicate titles.
3. Improve 4 pages ranking in positions 6–12 by adding missing subtopics and internal links.
4. Remove or update 2 thin pages with no traffic.

Keep the list to 5–10 items max for your first audit. Finishing a short list beats starting a long one.

Common Beginner Mistakes

• Chasing every red flag. Site Audit flags many minor issues. Fix what affects rankings and users first.
• Trusting estimates as exact numbers. Ahrefs data is modeled, not measured from your analytics.
• Auditing a huge site too early. Start small to learn the interface.
• Ignoring search intent. A page can be technically perfect but still fail if it doesn't match what searchers want.
• Forgetting to re-crawl. After fixes, run Site Audit again to confirm improvements.

Where to Go Next

Once your first audit is done:

• Compare with competitors using Site Explorer's Competing Domains and Content Gap reports.
• Track keyword rankings over time with Rank Tracker.
• Explore backlink opportunities in the Backlinks and Link Intersect reports.
• Set up recurring Site Audit crawls so new issues surface automatically.

Your first audit isn't about perfection — it's about building a repeatable habit: enter a target, read the key reports, pick the highest-impact fixes, and act. Do that once a month and your site's health compounds.

The three receivers serve different roles rather than competing directly: the ER12 and ER16 are Gemini-X PWM receivers aimed at RC models that need multiple PWM outputs, while the ER3 Pro is a compact three-channel option for smaller or simpler builds. If you are choosing between them, the deciding factors are how many PWM channels your model needs, how much space and weight you can spare, and whether your radio link supports the Gemini-X dual-band mode. Oscar Liang's review of the ER12, ER16 and ER3 Pro is the reference point here, and the details below stay within what that review and the site's published material support.

What "Gemini-X PWM" means in practice

Gemini-X refers to RadioMaster's dual-band 2.4GHz link scheme, where two frequency bands are used together to improve link robustness. The PWM part matters just as much for model builders: these receivers output traditional PWM signals, so each channel drives a servo, ESC or switch directly without needing a flight controller to decode a serial protocol.

That combination is what makes this family relevant to RC models — planes, boats, cars, or any build where you want servos plugged straight into the receiver. It is a different use case from a serial receiver feeding a flight controller over CRSF or SBUS.

How the three receivers differ

The pattern is straightforward: ER12 and ER16 scale up in channel count for models that need many independent PWM outputs, and ER3 Pro scales down to a minimal three-channel footprint. The review treats them as one family covering different model sizes rather than as alternatives to pick between on performance alone.

What to check before buying

Channel count

Count every function you need to drive independently — each aileron, elevator, rudder, throttle, flaps, retracts, lights, and any switched accessory. If that number exceeds three, the ER3 Pro is out and you are choosing between the ER12 and ER16 based on how much headroom you want. Buying exactly to your current count leaves no room for a later addition.

Radio compatibility

Gemini-X is a RadioMaster link feature, so confirm your transmitter supports it before assuming you get the dual-band benefit. A receiver that works is not the same as a receiver that works in the mode you bought it for.

Physical fit

The ER3 Pro's advantage is its small size, which matters in tight fuselages and small airframes. The larger receivers need somewhere to sit and something to mount to. Check the dimensions against your model's available space rather than assuming a bigger receiver will fit because the model is bigger.

Power and wiring

PWM receivers need their output rails and signal wiring planned like any traditional setup. Decide early whether you are powering servos from a BEC and how you will route the leads, because that affects where the receiver can physically go.

Where the review's experience is useful

Oscar Liang's review covers the ER12, ER16 and ER3 Pro together, which is the practical way to read it: the useful information is the relative positioning between the three, not an isolated verdict on one. When you read it, focus on the observations about channel layout, physical size and how each unit is intended to be used in a model, since those are the details that decide whether a receiver suits your build.

If you are still at the stage of choosing your first FPV or RC gear rather than picking between these three, the site's beginner-oriented material is a better starting point than a receiver comparison — the receiver decision only becomes meaningful once you know what you are building.

A reasonable way to decide

• Building a small, light model with three or fewer controlled functions: ER3 Pro.
• Building a model with several servos and switched accessories: ER12, unless your count is high enough that you want the ER16's extra outputs.
• Unsure of your final channel count: lean toward the higher-count receiver, since unused PWM outputs cost nothing but a missing one forces a rebuild.
• Confirm Gemini-X support on your transmitter and check physical dimensions against your airframe before ordering either way.

To test an FPV drone with a multimeter, you mainly need three modes: continuity (beep) to check for shorts and broken connections, DC voltage to confirm power is reaching the right places, and resistance to trace faults when continuity alone isn't clear. The workflow that matters most is checking for shorts before you plug in a battery, then verifying voltage after. Oscar Liang's tutorial on this calls a multimeter "one of the first tools you should get when getting into FPV," and frames it as a roughly $10 investment — cheap relative to the parts it protects.

This guide covers what each mode does, the specific test points on a typical quad, and the mistakes that turn a quick check into a fried flight controller.

The three modes you actually use

You will not need AC voltage, current (A), or capacitance for routine FPV checks. If your meter has an auto-range function, use it; if not, start on the highest range and step down.

Before you power anything: the short check

This is the single most valuable habit. A short between battery positive and negative will destroy components the instant you connect a battery — and it is invisible to the eye.

1. Set the meter to continuity mode.
2. Touch the probes together to confirm it beeps (this verifies the meter and leads work).
3. On the drone, with no battery connected, place one probe on the main positive pad (or battery connector positive pin) and the other on the main negative pad.
4. Expected result: no beep, or a very high resistance reading. A continuous beep means a short — find it before going further.

Repeat the same check across the positive and negative rails of your ESC, and across any 5V or 9V BEC output pads if you can reach them.

If it beeps

Do not connect a battery. Common causes:

• Solder bridge between adjacent pads (look under magnification)
• A wire strand shorting across two pads
• A damaged component or a connector inserted backwards
• Conductive debris or excess flux bridging a gap

Clean the area, re-inspect, and re-test. Only proceed when the beep is gone.

After power-up: voltage checks

Once the short check passes, connect a battery (props off, ideally on a bench with nothing flammable nearby) and switch to DC voltage.

Battery input: probe the main positive and negative pads. You should read close to the battery's nominal charged voltage — a fully charged 6S LiPo reads about 25.2V, a 4S about 16.8V. A reading far below that points to a bad connector, a damaged cell, or high resistance in the wiring.

Regulated rails: most flight controllers and VTXs run on 5V, and some on 9V or 12V. Probe the relevant pad against ground. If a 5V rail reads 3V or fluctuates, the regulator is failing or being overloaded — a common cause of receivers dropping out mid-flight.

Receiver and GPS: confirm they see the voltage they expect. A receiver rated for 5V fed 9V is a dead receiver.

Continuity checks on the bench

With the battery disconnected, continuity mode answers "is this connection intact?":

• Motor wires to ESC: each motor phase should show continuity from the motor pad to the ESC output. No beep means a broken joint or a broken wire inside the insulation.
• Signal wires: check that a signal pad connects to the correct pin on the connector or FC pad. This catches swapped or misrouted wires before they cause a confusing bench test.
• Grounds: all grounds should be common. If two ground points don't show continuity, you have a floating ground, which causes erratic behaviour.

Note that continuity mode on some meters also reads through components, so a beep doesn't always mean a direct wire — it can mean a path through a resistor or diode. When in doubt, switch to resistance and compare the value against what you expect.

Common mistakes and how to avoid them

• Probing a live circuit in continuity or resistance mode. You can get false readings and, on some meters, damage the meter. Always disconnect power for these modes.
• Forgetting to zero the leads. Touch the probes together first. A meter with damaged leads may never beep, giving you a false "no short" result.
• Assuming no beep means no short. A short through a high-resistance path may not trigger the beeper. Use resistance mode to check the actual value.
• Testing with props on. Never. A motor that spins unexpectedly during a voltage check is a serious injury risk.
• Chasing a fault with the battery connected. Most diagnosis happens unpowered. Power up only to confirm a fix, not to hunt for it.

A practical order of operations

1. Visual inspection and cleaning.
2. Continuity check across main power rails — no battery.
3. Continuity check on motor phases and signal wires — no battery.
4. Connect battery, props off.
5. DC voltage check on battery input, then each regulated rail.
6. Disconnect, fix anything out of spec, repeat from step 2.

This sequence catches the failures that cost the most money (shorts, reversed polarity) before they can do damage, and it uses only the modes a basic meter provides. Oscar Liang's framing is worth repeating: the tool is inexpensive, but the habit of checking before powering is what actually protects your build.

5.8GHz FPV video runs on a set of predefined channels, each tied to a specific frequency in MHz. To get a working link, your VTX (video transmitter) and VRX (video receiver, usually in your goggles) must be on the same frequency — not just the same channel name. The practical catch: analog and digital systems divide that band differently, and even analog gear from different brands can label the same frequency with different channel numbers. So the reliable approach is to match frequencies, then confirm the channel name.

The 5.8GHz band and why channels exist

5.8GHz is one of several bands used for FPV video (others include 1.2GHz and 2.4GHz), and it is the most common for both analog and digital systems. Because many pilots fly near each other, the band is split into channels so multiple video links can operate at once without stepping on each other.

Each channel is just a named frequency. When you select "channel 4" on a VTX, you are really telling it to transmit on one exact frequency in MHz. Two devices only work together if those frequencies match.

Analog vs digital: different channel plans

This is the part that trips people up. Analog and digital FPV do not share the same channel layout.

• Analog: Uses established channel groups (often called bands, such as A, B, E, F, R, and others depending on the manufacturer). Each band contains a set of channels, and the frequency for a given channel number can differ between bands.
• Digital: Systems like DJI, Walksnail, and HDZero use their own channel/frequency arrangements, and these generally do not line up with analog channel numbers.

The result: an analog channel 4 and a digital channel 4 are not the same frequency. You cannot assume compatibility from the channel number alone.

How to use a frequency chart to match devices

A 5.8GHz FPV channel and frequency chart lists each channel name next to its frequency in MHz. Use it like this:

1. Find your VTX's frequency for the channel you want (or pick a frequency directly if the VTX supports manual entry).
2. Look up the same frequency in your goggles'/VRX's chart.
3. Set the VRX to the channel that carries that frequency.
4. Power up and confirm you have a clean image.

If your VTX and VRX both support direct frequency selection, skip the channel names entirely and set both to the same MHz value. That removes any ambiguity from mismatched band labels.

Quick reference example

The exact frequencies depend on the specific band and system, so always check the chart for your actual hardware rather than relying on a memorized number.

Avoiding same-frequency interference

Because channels exist to let multiple pilots share the band, the main rule is simple: don't transmit on a frequency someone nearby is already using.

• Coordinate before you power up. On a group flight, assign each pilot a distinct frequency.
• Watch for adjacent-channel bleed. Channels that are close in frequency can still interfere, especially at high VTX power. Spacing pilots further apart in the band helps.
• Lower VTX power when flying close together. Less power means less spillover onto neighbors.
• Check your own gear. A VTX left on a conflicting channel will wipe out another pilot's feed even if your own image looks fine.

Compatibility notes across devices

• Same brand, same system: Usually straightforward — matching channel names generally means matching frequencies.
• Different analog brands: Channel numbers may not correspond. Verify with the frequency chart.
• Analog VTX + digital VRX (or vice versa): These are different systems and are not expected to work together on the same channel plan.
• Digital to digital across brands: Treat each ecosystem separately; do not assume shared channels.

When in doubt, the frequency in MHz is the ground truth. Channel names are a convenience layer on top of it.

What beginners should take away

If you are new to FPV, the single most useful habit is to think in frequencies, not channel numbers. Learn where your gear's frequency chart is, match the MHz value between VTX and VRX, and coordinate frequencies with anyone else flying. That covers the vast majority of "why is my video not working" and "why did I knock out my friend's feed" situations.